Thermal time-delay relay



p 14, 1964 H. M. PERKINS ETAL 3,129,306

THERMAL TIME-DELAY RELAY Filed Aug. 1, 1960 INVENTORS Herbert M. Perkins BY William Chokeres ATTORNEY.

United States Patent 3,129,306 THERMAL TIME-DELAY RELAY Herbert M. Perkins, Livingston, and William Chakeres, Newark, NIL, assignors to Thermal Controls, Inc, Arlington, N.J., a corporation of New Jersey Filed Aug. 1, 1960, Ser. No. 46,558 17 Claims. (Cl. 200-122) This invention relates to thermal relays of the timedelay type.

An object of this invention is to provide an improved thermal time-delay relay which is of simple construc tion, is highly resistant to extreme changes in environmental conditions, which comprises a minimum number of parts and which is economical to manufacture.

While a number of thermal relay constructions have been proposed, in many cases, such constructions are overly sensitive to vibration and other extreme variations in conditions of use. Accordingly, another object of this invention is to provide an improved thermal relay in which the parts thereof are of such a nature and arrangement as to be highly resistant to shock and vibration, yet adapted for precision operation.

A further object of this invention is to provide an improved thermal relay construction which includes precision means for regulating the operational time delay of the device; such adjusting means being proof against variations in environmental conditions.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

In the drawing,

FIG. 1 is a vertical sectional view of a thermal timedelay relay embodying the invention;

FIG. 2 is a cross sectional view taken on the line 22 of FIG. 1; and

FIG. 3 is a diagrammatic representation of the circuitry of the relay.

Referring in detail to the drawing, the thermal timedelay relay embodying the invention, is shown at It). The same comprises a header 11 which carries mounting and electrical connecting pins 12, 13, 14, 15, 16, 17 and 18 which are fixed in spaced relationship in an electrical insulating body 19, such as vitreous material which is fused to said pins and to a metal rim 20. A casing 29A may be provided for enclosing and sealing the device from the atmosphere, the lower end of the casing 20A being soldered or otherwise secured to metal rim 20. The interior of the casing 20A may be evacuated or gasified in a manner known in the art.

The relay further includes a heater assembly 21 which may take the form of a metal envelope 22 which encloses a conventional wire resistance heating unit, not shown, with leads 23 from the heating unit connected to electrical input pins 13, 14 to allow for the energization of said heating unit.

A transverse mounting strip 22A is welded or otherwise secured to mounting pins 12, 15. A thermally extensible metal strip 24 is secured to a face of envelope 22 at midpoint therein, said strip 24 having opposite ends projecting beyond the opposite ends of said envelope. The lower end of strip 24 is welded to cross strip 22A, While the upper end of said strip 24 is secured to the upper end of an elongated compensating member 25 by means of a hinge strip 26. Compensating member 25 is substantially equal in length to the strip 24, and may be in channel form with a rectangular cutout 27 in the web thereof, for the purpose hereinafter appearing.

A horizontally disposed, fixed contact strip 28 is secured at one end thereof to electrical connector pin 16. A contact 29 is arranged for movement toward and away from contact strip 28. Contact 29 is fixed to the lower end of an elongated flat spring member 30, which is fixed 3,129,306 Patented Apr. 14, 1964 at its upper end to an inverted L shaped contact arm 31.

Contact arm 31 comprises a short section 32 which is hingedly secured to the upper end of compensating member 25 by a hinge strip 33. The long section 34 of contact arm 31 extends downwardly through cutout 27 in compensating member 25 and terminates at its lower end short of the upper edge of contact strip 28. Spring member 30 is preloaded in respect to arm section 34 by a dimple 35 formed in the lower portion of the spring member and which bears on an opposed surface portion of arm section 34.

The lower end of compensating member 25 is hingedly connected to mounting pins 17, 18 by means of a hinge strip 36 welded to a cross strip 37, which in turn is welded to pins 17, 18. The bottom edge of member 25 is adjacent the top edge of cross strip 37 and arranged for angular, hinged movement relative to said cross strip 37.

Strip 24 and member 25 being of substantially the same length, an isosceles triangle structure is formed, with the lower end of strip 24 anchored to cross strip 22A and the lower end of member 25 hingedly connected to cross strip 37. Strip 24 and member 25 are formed of the same metal, such as stainless steel or the like.

When heater assembly 21 is energized by current fed to input pins 13, 14; strip 24 will extend and the triangular structure including said strip 24 will have lateral movement at its apex portion in the direction indicated by arrow A. Since contact arm 31 is mounted on compensating member 25, arm 31 would move in the same direction. However, movement of arm 31 is modified by providing fulcrum means 33 in engagement with arm section 34 intermediate the ends thereof.

Fulcrum means 38 comprises an elongated, channel shaped member 39 anchored at its lower end to cross strip 37 and carrying on an upper portion thereof a spherical fulcrum member 40 of low friction material, such as a glass bead or the like; said member 40 bearing on the upper end of spring member 30 adjacent its point of attachment to contact arm section 34.

Fulcrum means 38 further includes a short, angularly related arm portion 41 extending from the upper end of member 39 which acts as a camrning means in conjunction with a vertically disposed adjusting screw 42 mounted in a threaded sleeve 43 fixed to a cross partition 44 at the upper end of casing 20A. Screw 42 includes at its lower end a vitreous, electrically insulating ball portion 45 which bears on arm portion 41.

An inverted V-shaped spring 45A having one arm 46 fixed at its lower end to cross strip 22A and its other arm 47 fixed at its lower end to the lower end of arm section 34, maintains arm section 34 in engagement With fulcrum member 40.

It will be apparent, that upon energizing heating assembly 21, thermally extensible strip 24 will elongate and concomitantly move compensating member 25 in the direction indicated by arrow A. Contact arm 31 will tend to move in the same direction, except that fulcrum member 42 is effective to actuate arm section 34 as a lever, with the lower end of said arm section 34 swinging in a direction indicated by arrow B, opposite to direction A, to move contact 29 into engagement with contact strip 28. Thus, a circuit including pins 16, 17 will be closed. Furthermore, arm 31 while acting as a lever, also has pivotal movement relative to compensating member 25 by way of hinge 36.

The location of contact 29 with respect to contact strip 28, when heater assembly 21 is deenergized, is adjusted by means of screw 42, which is accessible by removing the cover of easing 20A. By turning screw 42 in one direction or the other, member 39 is shifted laterally to adjust the position of fulcrum member 40 and thereby ad- 6)) just the position of spring 30 which carries movable contact 29. Member 39 is resiliently biased while screw 42 is turned in either direction, through the action of spring 45A. Spring 45A also acts to damp the lower end of contact arm 31, thereby increasing resistance to shock and vibration.

The preloading of spring 30 by means of dimple 35 provides a differential spring rate on spring 30, thereby assuring positive contact pressure as between contact 29 and contact strip 28 before spring 30 is displaced with respect to arm section 34' as arm section 34 travels in the direction indicated by arrow B. Also, little resistance is offered to the overtravel of arm section 34, thereby avoiding strains on the structure and improving its resistance to changes in environmental conditions. As various changes might be made in the embodiment of the invention herein disclosed without departing from the spirit thereof, it is understood that all matter herein shown or described is illustrative and not limiting except as set forth in the appended claims.

We claim as new and desire to protect by Letters Patent:

1. A thermal relay comprising a base, a fixed contact on said base, an elongated thermally expansible member upstanding from said base with one end thereof anchored to said base, an elongated compensating member upstanding from said base with one end thereof anchored to said base in displaced relation to the one end of said expansible member, hinge means interconnecting the other ends of said expansible and compensating members, an elongated contact arm hingedly connected at one end thereof to the interconnected portions of said expansible and compensating members, a movable contact, means on said contact arm for mounting said movable contact at a point beyond the free end of said contact arm and in opposed relation to said fixed contact, the interconnected portions of said expansible and compensating members and said contact arm being movable laterally in one direction in response to thermal expansion of said expansible member, and fulcrum means operatively related to said contact arm for pivoting said contact arm and the associated contact mounting means in response to the movement of the interconnected portions of said expansible and compensating members whereby to move said movable contact laterally in a direction opposite to said one direction and toward said fixed contact.

2. A relay as in claim 1 and including means for adjusting the position of said fulcrum means to adjust the initial distance between said contacts.

3. A relay as in claim 1 and including means for resiliently biasing said contact arm into engagement with said fulcrum means in all positions of said compensating member.

4. A relay as in claim 3 wherein said fulcrum means includes an elongated fulcrum supporting member, means for fixing one end of said supporting member, a cam surface portion on the other end of said supporting member, and adjustable cam means bearing on said cam surface for deflecting the other end of said supporting member to adjust the position of said fulcrum means.

5. A thermal relay comprising an elongated thermally expansible member, an elongated compensating member, means hingedly connecting said members at one end thereof, means for fixedly securing the other end of said expansible member, means for hingedly securing the other end of said compensating member, a contact arm connected at one end thereof to said compensating member for movement relative thereto, a contact, means for mounting said last mentioned contact on said arm, a fixed contact, and independent fulcrum means spaced from said expansible and compensating members for engagement with the assembly of said contact mounting means. and said arm for pivoting said assembly in response to concomitant movement of said members in one direction upon thermal expansion of said expansible member, to

move said contact in the opposite direction whereby to engage said contact with said fixed contact.

6. A thermal relay comprising a pair of expansible elongated members interconnected at one end thereof, the other ends of said members being displaced from each other, means for securing the other ends of said members, means for heating one of said members to elongate said one member and to move the interconnected members in one direction, an arm secured at one end thereof to the other of said members adjacent the one end thereof, for movement relative to said other member, a movable contact, a fixed contact, an elongated spring member secured to one end thereof to said arm, said movable contact being mounted on the free end of said spring member in opposed relation to said fixed contact, fulcrum means independently related to said interconnected members, said fulcrum means being engageable with the assembly of said arm and spring member to pivot said assembly in response to the movement of the interconnected members in said one direction to move the free end of said spring member in a direction opposite to said one direction, whereby said movable contact engages said fixed contact.

7. A relay as in claim 6 wherein said arm is hingedly connected at said one end thereof to the other of said members.

8. A relay as in claim 6 and further including spring means for biasing said other member into engagement with said fulcrum means.

9. A relay as in claim 8 and further including means for preloading said elongated spring member.

10. A relay as in claim 8 and further including means for adjusting the position of said fulcrum means to adjust the initial spacing between said contacts while said one member is in an unheated condition.

11. A thermal relay comprising a supporting header, a thermally expansible member, a compensating member, means interconnecting said members at one end thereof, means for mounting the other-ends of said members on said header in displaced relation to each other, a contact arm hingedly mounted at one end thereof on said compensating member for movement relative thereto, a contact, means for mounting said contact adjacent the other end of said contact arm for conjoint movement therewith, a fixed contact on said header in opposed relation to said first mentioned contact, fulcrum supporting means, fulcrum means on said fulcrum supporting means for operative engagement with said contact arm, means for heating said expansible member to cause lateral displacement of the interconnected portions of said members in one direction, said fulcrum means being operative to pivot the other end of said contact arm in the opposite direction to cause the contact thereon to engage said fixed contact.

12. A relay as in claim 11 and further including means for resiliently biasing said contact arm into engagement with said fulcrum means.

13. A relay as in claim 12 and further including means for adjustably displacing said fulcrum supporting means for adjusting the position of said fulcrum means relative to said contact arm.

14. A relay as in claim 13 wherein said fulcrum supporting means comprises an elongated member upstanding from said header, said adjusting means being engageable with the free upper end of said upstanding member, said resilient biasing means being operative to maintain the upper end of said upstanding member in engagement with said adjusting means in all positions of'said adjusting means.

15. A thermal time delay relay comprising a header, a thermally expansible member upstanding from said header, a compensating member upstanding from said header, means connecting the upper ends of said members together, means for fixing the lower ends of said members on said header in displaced relation to each other, means for heating said expansible member, an

angular contact arm having short and long arm sections, means for hingedly connecting the short arm section of said contact arm to said compensating member for conjoint movement therewith and for pivoted movement relative thereto, said compensating member being formed with a cut out portion along the length thereof, the long arm section of said contact arm extending downwardly through the cut out portion of said compensating member, a movable contact, means on said contact arm for mounting said movable contact below the lower end of the long arm section of said contact arm, a fixed contact on said header between the lower ends of said expansible and compensating members and in opposed relation to said movable contact, fulcrum means operatively related to the long arm section of said contact arm for pivoting said long arm section in a direction to engage said movable contact with said fixed contact in response to the thermal elongation of said expansible member and the conjoint movement of said compensating member therewith.

16. A relay as in claim 15 and further including means for resiliently biasing said long arm section of said contact arm into operative relation with said fulcrum means.

17. A relay as in claim 15 wherein said contact mounting means comprises elongated spring means connected at one end to the long arm section of said contact arm, said movable contact being mounted on the free end of said spring means.

References Cited in the file of this patent UNITED STATES PATENTS 2,700,084 Broekhuysen Jan. 18, 1955 2,809,253 Broekhuysen Oct. 8, 1957 2,817,731 De Falco Dec. 24, 1957 2,928,918 Payne Mar. 15, 1960 2,948,788 Broekhuysen Aug. 9, 1960 2,961,516 Broekhuysen Nov. 22, 1960 

1. A THERMAL RELAY COMPRISING A BASE, A FIXED CONTACT ON SAID BASE, AN ELONGATED THERMALLY EXPANSIBLE MEMBER UPSTANDING FROM SAID BASE WITH ONE END THEREOF ANCHORED TO SAID BASE, AN ELONGATED COMPENSATING MEMBER UPSTANDING FROM SAID BASE WITH ONE END THEREOF ANCHORED TO SAID BASE IN DISPLACED RELATION TO THE ONE END OF SAID EXPANSIBLE MEMBER, HINGE MEANS INTERCONNETING THE OTHER ENDS OF SAID EXPANSIBLE AND COMPENSATING MEMBERS, AN ELONGATED CONTACT ARM HINGEDLY CONNECTED AT ONE END THEREOF TO THE INTERCONNECTED PORTIONS OF SAID EXPANSIBLE AND COMPENSATING MEMBERS, A MOVABLE CONTACT, MEANS ON SAID CONTACT ARM FOR MOUNTING SAID MOVABLE CONTACT AT A POINT BEYOND THE FREE END OF SAID CONTACT ARM AND IN OPPOSED RELATION TO SAID FIXED CONTACT, THE INTERCONNECTED PORTIONS OF SAID EXPANSIBLE AND COMPENSATING MEMBERS AND SAID CONTACT ARM BEING MOVABLE LATERALLY IN ONE DIRECTION IN RESPONSE TO THERMAL EXPANSION OF SAID EXPANSIBLE MEMBER, AND FULCRUM MEANS OPERATIVELY RELATED TO SAID CONTACT ARM FOR PIVOTING SAID CONTACT ARM AND THE ASSOCIATED CONTACT MOUNTING MEANS IN RESPONSE TO THE MOVEMENT OF THE INTERCONNECTED PORTIONS OF SAID EXPANSIBLE AND COMPENSATING MEMBERS WHEREBY TO MOVE SAID MOVABLE CONTACT LATERALLY IN A DIRECTION OPPOSITE TO SAID ONE DIRECTION AND TOWARD SAID FIXED CONTACT. 